1. Schrödinger’s cat is alive.2. Schrödinger’s cat is dead.3. Exactly one of statements 6 and 9 is true.4. Exactly one of statements 2 and 6 is false.5. Statements 4, 5 and 10 are all false.6. Exactly one of statements 1 and 10 is false.7. Exactly 5 statements are true.8. Exactly one of statements 3 and 10 is false.9. Exactly one of statements 6 and 10 is true.10. Exactly one of statements 1 and 2 is false.11. Statements 1, 8 and 11 are all false.

Enter your answer as a list, in numerical order, of the number(s) of the statements that are definitely true, as a single string with no spaces, such as, for example, 25811.

Considering the question carefully I have found a third valid answer. The firstmatches the official answer. The second is the variation the puzzle builder missed. But there is a third answer – and you will love it ! !! !!!!

looks like I have to scratch the third answer as I found one error when testing in the morning (I guess I rushed to post too soon on this one). The other two answers are still valid though and have passed all testing.

Last weeks took me hours (although that did include a crash course in basic cyrptology at simon singh’s website), yet this one I found quite straightforward. I suspect that although my woeful lack of physics knowledge hindered me slightly last week, it is perhaps an advantage this time…

It is purely a traditional logic puzzle. I think the original introduction to these 5 puzzles said that they could be solved with logic and without detailed knowledge of physics. Don’t try to make it too complex!There is only one correct answer that is logical.

I agree with Cherokee, without revealing the answer, I don’t like the answers to 1&2.
assuming you look to find out then surely it could be one OR the other, and if you don’t look, then it could be either.
You either know with certainty and it is one OR the other, or you DON’T know with certainty and therefore it would be neither…
Not convinced.

#177, took about 10 mins. Nice bit of deduction involved. I liked last weeks too, again about 10mins, #4876. It was fun seeing the message appear before your eyes, word by word. There is only one answer that is definitely right.

Didn’t like it. Not only does it assume classical physics (ie the cat is either one or the other, not both), it seems to require you to deduce something using statement 11, but 11 is a Cretan paradox from which nothing follows except that it can’t be definitely true.

‘This sentence is false and Statement 1 is true’ has exactly the same content as ‘This sentence is false and Statement 1 is false’ … neither give you any information about Statement 1.

stringph I didn’t use statement 11 to try and determine the truth or falsehood of statements 1 and 8. I started with the cat! You might have found this easier if it hadn’t been labelled ‘Schrodinger’s cat’!

Is this a logic puzzle or do you bring meaning from the outside world? Statements 1 and 2 say nothing on their own but have to be evaluated in terms of the other statements. They are independent. Could have said Schrödinger’s apple is red, Schrödinger’s apple is green, then red and green can exist together. You can still evaluate the logic. Having alive or dead in there is bringing in outside knowledge beyond logic as is cat.

That’s exactly what I did. And then applied a bit of ‘Conan Doyle reasoning’, ie once you’ve removed everything that’s false then whatever remains, however improbable, must be the truth. Also, I didn’t let any quantum theory cloud my thinking, which seemed to work.

I agree with Andrew W. When you follow the logic, statement 11 is as solvable as statement 5. Also, the question asks for the numbers of statements that are ‘definitely true’, not those that can be true or false, which seems to have confused some people.

Agreed.
I initially thought the setters were being clever by allowing 2 answers. However only one is accepted for submission, and both give the same outcome for the cat. Think they have screwed up with this one.

#197 – Seems that the solution requires as much philosiphizing as logic. I had to make certain assumptions that I would have preferred not to make in order to arrive at this solution.
It appears there are more than 1 way to skin a cat!

I agree that this puzzle wasn’t as delightful as the first, but it was satisfying to solve it nevertheless. It took up more paper than the last one, too (I tried using a computer but the spreadsheet software I used didn’t like self-referential formulas!) I came in 123rd, and it took me probably an hour all told (I was doing it in snippets of time throughout the day).

Person 622, took a while, not satisfied with the answer (agree with Catweazle above) and the earlier comments about Statement 7. Once I challenged some interpretations, worked through it. Will ponder some more, but look forward to seeing a worked solution…

#983 Got it after a few minutes but couldn’t complete it till just now as ive been at school. I think there are two different solutions with different outcomes for the cat but there are some statements that must always be true and some that must always be false

#1022, I tried a variety of ways to solve, with network diagram and random trial and error, finally spotting the route through the maze. I really enjoyed this one, looking forward to the next challenge.

Interestingly, there is a unique solution for which the cat can be dead, alive, or in a quantum superposition of the two states. Once the cat’s state is determined, the answer changes, but you need to know whether it is alive or dead to get the solution which the puzzle is looking for.

Statement 11 is the key to solving this. The cat can be in one of 4 states (alive, dead, both or neither). For only one of these can the state of statement 11 be deduced, therefore that’s the correct state of the moggy.

2 3 6 10 makes 1 and 8 false and 11 therefore becomes a paradox. I think that’s the crux of the “correct” solution, though to me it seems like a case of the tail wagging the dog (or should that be cat).

Statement 5 says statement 5 is false – this is like saying you are lying: are you then telling the truth, in which case you are not lying, in which case the statement is false, in which case you are lying…etc….

Statement 7 is true if you include it in your ‘true’ list, but false if you include it in your ‘false’ list – both ways appear correct to me.

Nothing to add apart from the fact that my Haynes workshop manual for a Mark IV Large Hadron Collider was of no use whatsoever. That is going back for starters. Oh, and my ordinal number isn’t even a prime, a square or anything.

#1403 I thought Last weeks puzzle was fun, but this one was fairly unsatisfying. I tried to use logic from the start to sort it out and was getting nowhere. Then I made an assumption (which I hate to do in logic puzzles) about the cat, and solved it in seconds.

Well, I make that 111 comments. Seems like some people prefer puzzles to physics. I don’t have time for this sort of thing I’m afraid. Especially since Schrodinger proposed his cat to demonstrate that the Copenhagen Interpretation led to a nonsense scenario. And it’s since been hijacked by quantum mystics.

Q7 is still making no sense to me and caused a lot of wasted time yesterday testing the both alive and dead / neither possibilities before forcing the issue and taking a punt. [yes i should have read the comments first] Anyone explain Q7?

Its vague but maybe “definitely true” means that the puzzle is valid only if that question is true and it only gives a valid answer to the puzzle when true and not when false. The puzzle is valid if q7 is true or false. So as we have a valid puzzle when q7 is false rules out that question being included in the exclusively true count. Or to paraphrase ‘true and only ever true case’.

I understand the Statement 7 conundrum…but I still get 2 ‘valid’ answers. The ‘officially’ correct version and the other one, mentioned above. As far as I can see they both work (maybe that’s the point!!). Also, regarding Statements 5 & 11, as they have only one possible (non-paradoxical) answer, neither gives any useful information about any other statement.

I would love to discuss the solution with you all, but for now my mouth must remain zipped! The solutions will be revealed, but not until everyone’s had a good chance to have a go at all the puzzles. I’m really pleased that people seem to be enjoying/squirming as much as I did at various points throughout the puzzle testing. Not long now till Puzzle 3….

Terrible puzzle, the wording of the question very clearly leads to statements 3, 4 & 10 being the only ones that are *definitely* true. The cat is neither *definitely* alive or dead according to the statements made. If you start making assumptions about the health of the cat there are, in fact, 4 possible answers. Please do better next time Louise.

@bod your statements are completely false. Simple logic, the puzzle prompt “Is Schrödinger’s cat alive or dead?”, and statement 10 “Exactly one of statements 1 and 2 is false” (which you said must be true) clearly mean that #1 and #2 CANNOT both be true. Therefore one statement MUST be true and the other MUST be false.

Victoria – your assumption that the cat cannot be both alive and dead is as suspect as an assumption that someone cannot be in many places at the same time, or that an event in the present cannot affect an event in the past – it’s quantum physics, and the cat is a quantum physics subject.

I need to start trying these the day they are published. Both puzzles from last week and this week only took me a few minutes. It is currently just past 12 EST and the forum shows 5pm so I’m guessing these are published around 5AM EST on Tuesday?

This is not a logic puzzle. It is a joke… an Andy Kaufman style joke. Start with the result you hope for work it out from there and it will take minutes. There are at most two possible answers this way. If you start with the facts, you will be sorely dissapointed. #1688

I did it using algebra, I wrote each statement as an equation, then simply substituted and reduced until I was left with a definite set of true / false values. Quite fun, took me ages to realise this was the technique.

Took me about 10 minutes using pen and paper. No diagrams or functions or anything, just 13 bullet points with T/F behind them, the rest was brain gymnastics.

Disappointed with this one. The answer is completely arbitrary, to figure it out you essentially have to lower your wisdom to that of someone who has no clue what the schrodinger’s cat thought experiment was meant to demonstrate, and then gamble on one of 4 correct answers (you cannot make definite statements about an unknown, and therefor you cannot even assume that the answers to 1 and 2 are opposite, hence 4 possibilities, not 2).

The only actual correct answer is the one answer you cannot enter: none of the statements can be said to be definitely true.

Nothing arbitrary and no gambling required, just logic. I think Schrödinger’s cat is more of a Cheshire cat smiling at what our macro world would be like if it followed the quantum laws. This is a good puzzle very much in the spirit of the quantum as they both make people uncomfortable. Just glad that this weeks problem “cohered” 😉

Schrodingers cat: What if doesnt exist observer outside box? Will cat be live and dead forever? We can go outside our universe and suppose that there doesnt exist observer. So outside our universe is cat live and dead forever??

What does it mean?? From this we can say that if we are not able observe particles or matter then this matter is in superposition and we cant say about more its qualities. But maybe we can observe just one part of its qualities ( that this matter is partly in superposition and partly is wave function colapsed ). This is case of dark matter.

If the question is, “Which statements can only take the value true, when the whole set of statements is self-consistent?” then neither of the potentially paradoxical statements can be paradoxical. I started from there and the required answer (which is the only correct answer to the above interpretation of the question) follows.

If you think “paradoxical” is a different intrinsically consistent state for an individual statement, then the answer is, “None of the statements is definitely true. (But there are some which are definitely false).”

If you are still stuck this may help:
1) Pretend it’s your cat.
2) Guess Q1
3) Answer the rest in this order:
Q2,Q10,Q6,Q4,Q5,Q9,Q3,Q8,Q11,Q7
4) Enter and see if you have the solution.
5) If not, go back and change Q1 and repeat.
Hint: Think very carefully about Q7……

Reading through it, I got quite confused. Just wrote a list in sequence, labelling each number as ‘true’ or ‘false’, and worked it out in a few minutes – not quite as difficult as it seems initially.
You do need to think pretty carefully about statement 7, though.

Hmm. Got it eventually (#2107) but only after reading the various comments – especially the hint from Dead or Alive…

Again, I was looking for too much complexity (i.e., from quantum mechanics). Unfortunately, you have to neglect quantum mechanics to get to the answer, and this was somewhat misleading, especially given the way the question was posed…

I’m a bit lost… I have 2 solutions for this, and only one seems to be accepted. I’m not talking about with and without 7, in which case I’d have 4 solutions, but I assume these two would only be acceptable if we were allowing for multiple worlds. I’ll give my second solution here, because it is apparently a wrong answer, so I’m not giving away the correct answer. My second solution is 23610. I wonder if someone coming across this could tell me why this is wrong?

Just to add… I’ve just found C Pearce, and A Wren discussed this possibility further up on the 9th Aug ’13; this second solution makes statement 11 a paradox. But to my mind, this would make 11 neither true nor false, so can basically be ignored since it cannot provide any useful information, making this solution acceptable.

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